Siena climbed five points clear of the Serie A relegation zone with a narrow 1-0 home win over Roma on Monday night.
Emanuele Calaio converted a penalty early in the second half after Simon Kjaer brought down Mattia Destro to settle the game. However, the Danish defender vented his anger at the decision after the game on Twitter.
He wrote: "So frustrated. That was not a penalty. Not even close. Did absolutely nothing to bring #Destro down. I admit my mistakes, but this was not my mistake! The ref should have seen it better... We were not playing well against Siena but shouldn't lose like that. I feel cheated. I am shocked here after the game: #Destro throwing himself to the ground. Should take more than a soft wind to make a man fall."
The win at the Artemio Franchi stadium was Siena's first since January 4 and lifted the Tuscan outfit into 16th place.
For Roma it was a seventh defeat of the campaign and saw them miss the chance to leapfrog Inter Milan into fifth in the standings.
Napoli won their first league game since January 8 by defeating Chievo 2-0 at the Stadio San Paolo.
Miguel Britos and Edinson Cavani scored the goals for Walter Mazzarri's men in the first half and Chievo were unable to respond.
The result takes Napoli up to within a point of sixth-placed Roma, giving them a three-point cushion over Palermo, while Chievo missed the chance to pull 12 points clear of the relegation zone.